上一篇主要介绍了NHibernate映射文件的基础配置,这篇我们介绍下NHibernate的一对多及多对一配置(文中我直接使用双向关联,即一和多两端都配置,开发中可以只使用一端),同时略带介绍下NHibernate.Mapping.Attributes方式配置表映射。
首先,我们使用Parent和Children两个类,Parent为一端,Chrildren为多端。
下面是Parent类和映射文件配置:
namespace NHibernateStudy.OneToMany { public class Parent { public virtual String Id { get; set; } public virtual String Name { get; set; } public virtual IList<Children> Children { get; set; } } }
<?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="NHibernateStudy" namespace="NHibernateStudy.OneToMany"> <class name="Parent" table="parents"> <id name="Id" column="id" type="String"> <generator class="uuid.hex" /> </id> <property name="Name" column="name" type="String" /> <bag name="Children" table="children" inverse="true" cascade="all"> <key column="parentid" /> <one-to-many class="NHibernateStudy.OneToMany.Children"/> </bag> </class> </hibernate-mapping>
其中cascade我配置了all,保证级联更新,若有其他需求可以使用none等值。
下面是Children类及配置文件:
namespace NHibernateStudy.OneToMany { public class Children { public virtual string Id { get; set; } public virtual string Name { get; set; } public virtual Parent TheParent { get; set; } } }
<?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="NHibernateStudy" namespace="NHibernateStudy.OneToMany"> <class name="Children" table="children"> <id name="Id" column="id" type="String"> <generator class="uuid.hex" /> </id> <property name="Name" column="name" type="String" /> <many-to-one name="TheParent" column="parentid" class="NHibernateStudy.OneToMany.Parent" /> </class> </hibernate-mapping>
其中需要注意,many-to-one中,column写的是当前表的字段——外键;而配置一端时,其中key里的column配置的是多端的字段,即子表里的外键,而非当期表字段。
配置文件中添加mapping:
<mapping resource="NHibernateStudy.OneToMany.Parent.hbm.xml" assembly="NHibernateStudy" /> <mapping resource="NHibernateStudy.OneToMany.Children.hbm.xml" assembly="NHibernateStudy" />
下面是使用方式过程:
#region 添加一对多关联数据 Parent parent = new Parent(); parent.Name = "parent" + DateTime.Now.ToString("MMddHHmmss"); parent.Children = new List<Children>(); Children child = new Children(); child.Name = "child" + DateTime.Now.ToString("MMddHHmmss"); child.TheParent = parent; parent.Children.Clear(); parent.Children.Add(child); session.Save(parent); session.BeginTransaction().Commit(); #endregion #region 查看多对一数据 IList<Children> children = session.CreateCriteria<Children>().List<Children>(); foreach (var item in children) { Parent itemparent = item.TheParent ?? new Parent(); Console.WriteLine(string.Format("ChildId:{0} Name:{1} ParentId:{2} ParentName:{3}", item.Id, item.Name, itemparent.Id, itemparent.Name)); } #endregion
下面介绍下Attributes方式配置映射文件。
首先添加NHibernate.Mapping.Attributes引用,可以在nuget中查找。
下面是配置的类,使用此法可以避免使用hbm.xml的繁琐,其中的属性与hbm.xml中的基本一致。
namespace NHibernateStudy { [Serializable] [Class(Table = "animals", Name = "NHibernateStudy.Animal,NHibernateStudy")] public class Animal { /// <summary> /// 主键 /// </summary> [Id(Name = "Id", Column = "id", TypeType = typeof(string))] [Key] [Generator(Class = "uuid.hex")] public virtual String Id { get; set; } [Property(Name = "Name", Column = "name")] public virtual string Name { get; set; } } }
不过需要注意的是,在代码中使用的时候,需要使用以下方式加载Mapping。
Configuration cfg = new Configuration(); MemoryStream stream = new MemoryStream(); NHibernate.Mapping.Attributes.HbmSerializer.Default.Validate = true; NHibernate.Mapping.Attributes.HbmSerializer.Default.Serialize( stream, System.Reflection.Assembly.GetExecutingAssembly()); stream.Position = 0; // Rewind cfg.Configure(); cfg.AddInputStream(stream); // Use the stream here stream.Close(); ISessionFactory sessionFactory =cfg.BuildSessionFactory(); ISession session = sessionFactory.OpenSession();
下面是具体使用过程:
#region NHibernate.Mapping.Attributes映射添加一条数据 Animal a = new Animal(); a.Name = "animal" + DateTime.Now.ToString("MMddHHmmss"); session.Save(a); session.BeginTransaction().Commit(); IList<Animal> an = session.CreateCriteria<Animal>().List<Animal>(); foreach (var item in an) { Console.WriteLine("Animal——ID: " + item.Id + " Name:" + item.Name); } #endregion